Ventricular assist devices, known as VADs, often include an implantable blood pump and are used for both short-term (i.e., days, months) and long-term applications (i.e., years or a lifetime) when a patient's heart is incapable of providing adequate circulation, commonly referred to as heart failure or congestive heart failure. According to the American Heart Association, more than five million Americans are living with heart failure, with about 670,000 new cases diagnosed every year. People with heart failure often have shortness of breath and fatigue. Years of living with blocked arteries and/or high blood pressure can leave a heart too weak to pump enough blood to the body. As symptoms worsen, advanced heart failure develops.
A patient suffering from heart failure may use a VAD while awaiting a heart transplant or as a long term destination therapy. A patient may also use a VAD while recovering from heart surgery. Thus, a VAD can supplement a weak heart (i.e., partial support) or can effectively replace the natural heart's function.
All ventricular assist systems (VAS) require several watts of power to provide cardiac support. Thus, patients using a ventricular assist system and their supporting caregivers or providers (hereinafter “users”) can use non-implanted replenishable and/or replaceable power supplies to maintain mobility. Such non-implanted power supplies typically include battery packs and AC wall power converters. The power from these sources may be conveyed to the VAD via a VAS controller using cables.
Existing products, however, use several power cables or a single large enclosure containing both a power source and a VAS controller. The use of several power cables requires users to manage multiple cables. A single large enclosure is cumbersome to wear on the body owing to the relatively large size of batteries and other energy storage devices realizable using present-day technology.
Additionally, while using existing portable, wearable energy sources, users have limited options for expanding the amount of wearable energy storage with present commercial products. Instead, many existing products employ a single energy storage configuration, typically a battery of fixed capacity. Some existing devices allow for optional larger capacity battery packs to be used in lieu of a standard battery pack.
Finally, for all existing products, depleted energy sources must be disconnected before new energy sources can be connected. If a failure occurs with an energy storage system, rendering it inoperable, a user must disconnect the failed energy source before connecting another one. During this time, the medical device may not have been functional or functioning at a reduced capacity. Accordingly, improved portable energy supply systems and related methods that do not have at least some of the above-discussed disadvantages would provide benefits to users of wearable or implanted medical devices.